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at full throttle 60+ my car dies like it governed

  
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at full throttle 60+ my car dies like it governed

 
gallegos2005 gallegos2005
I love my Chevy Chevette! | Posts: 12 | Joined: 09/11
Posted: 05/24/12
06:51 PM

Hi, im hoping someone might have ideas. i seem to have gotten my car running good i used a vacum gauge to tune the car and i have pretty steady vacuum at 16.5 hg vac (i live in denver co if that helps). Before i tuned it vacuum was way down to 10 hg vac. Before i tuned it & still after i tuned it im haveing a problem when i take it for a hard test run going through the gears when i hit 70+ mph(before tuning) now 80+ mph (After tuning) the cars power shuts down and i cant go any quicker. its like all the power just cuts out. i just put a new msd distribitor with vacuum and a msd 6al box because my last mallory broke(weights spring broke and chewed it up). just driving at 55 and the i step on it it will go past 80 mph im really not sure what going on could this be my cam? Also my transmission (700r4)is staring to slip but when my power stops at 80 mph my car does not rev up like a slipping tanny would.
thanks for your time
ryan  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 05/24/12
08:25 PM

shh... don' t tell anybody.. but MSD ready to run distributers have an adjustable REV-LIMITER built in..

you could have other problems.. and you will get questions to answer after testing..  

pepsi1 pepsi1
Big Block power for the win | Posts: 940 | Joined: 03/11
Posted: 05/24/12
08:48 PM

+1 Wayne

Once you get the rev. limiter adjusted properly. You need to get some air stuffed in the engine.What type of carb. do you have and what size is it?  

88chevytruck 88chevytruck
V-6 Camaros rule! | Posts: 60 | Joined: 05/12
Posted: 05/24/12
11:06 PM

And the msd 6 al box also has rev limter in it does it act like hitting a rev limter in 1 st gear and so on or just at 80 mph  

gallegos2005 gallegos2005
I love my Chevy Chevette! | Posts: 12 | Joined: 09/11
Posted: 05/25/12
07:30 AM

No, it dosent hit a rev limiter i have a 6000 chip in the box, unless your saying the distribitor its self has a rev limiter then could you please tell me how to check it. I have a 750 speed demon with a 268 xtream energy comp cam with cast iron vortec heads and the car has ran great untill my malory went out.My front vent tube on the carb it really pushing alot of vapor and balls of gas keep coming out(if this is a problem). my floats are middle sight glass and a pressure regulator can be set at 1psi still does it. my fuels lines arnt touching anything hot. I found another piece of info on the web it says ( the car will run great in town but after 55+ mph the tourque converter will over heat your motor and make it your motor shutdown) obviously thats in shorter terms, but does this sound right?  

gallegos2005 gallegos2005
I love my Chevy Chevette! | Posts: 12 | Joined: 09/11
Posted: 05/25/12
07:33 AM

Opps sorry, this just does it when im running through the gears hard hitting 80+ mph motor goes flat. when im just crusing 55 and punch it i can go 110mph easy no problems.  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 05/25/12
11:42 AM

i did not see what kind of fuel pump you have... mechanical or electrical..


i would want to do a full flow test.. into a clear clean plastic bottle...   if you have a mechanical fuel pump watch the pulses of fuel while somebody cranks the engine.. please disable the ignition system so NO sparks are created..  make sure the pulses are all  equal and full.. not diminishing..
you should get a pint in 10 to 15 seconds of cranking..

~~~~~~~~~~~~~~~~~~~~~~~~~~

if you have an electric pump...  how long does it take to make a quart...  under 15 seconds.    does the pump flow stay the same...

if you have an electric fuel pump...    check your ground wires...  what... yep..

battery negative to the engine block...
battery negative to the body..
engine to the firewall..
failure to have any of these three may results in serious problems. as the electrons flow from Negative to positive.. when you run hard though the gears .. the engine is straining against the motor mounts..  so if you don't have a proper ground between the engine and the body.. you may loose the ground and the fuel pump may slow..

if you have a hand held digital volt meter.. i have a 2 minute test..

set digital volt meter to 20 volts scale..
engine running.. headlights on..
1. battery negative to battery positive...  14.1 to 14.7 volts
2. battery negative to the engine block.. 0.04 volts
3. battery negative to the body.. 0.02 volts
4. Engine block to the body.. 0.02 volts..

please post your results by number.. i can do this test in under a minute..  try it on a different car...  

88chevytruck 88chevytruck
V-6 Camaros rule! | Posts: 60 | Joined: 05/12
Posted: 05/26/12
06:39 PM

I dont know if same for u as me but in my truck has 26 gallon tank and its bout 1 and half feet wide but 5 feet long and pick up is in middle of tank when I launch had if im anywhere near a quarter tank it will do same act like its running out of fuel in second gear from where fuel is running away from pick up and sucking air dosent do it if I get on it at 55 and dosent do it if I have half tank of gas. Scratched my head for a while throwed  parts at it even rebuilt a almost new carb  before I figured out what was going on with gas in tank getting a fuel cell 2 stop that problem dint know what kind of car u have might not be ur problem didnt have problem till changed tires and it really started leave hard  

gallegos2005 gallegos2005
I love my Chevy Chevette! | Posts: 12 | Joined: 09/11
Posted: 05/27/12
07:15 AM

Ok I will do this on my next set of days off thank you I'll let you know  

gallegos2005 gallegos2005
I love my Chevy Chevette! | Posts: 12 | Joined: 09/11
Posted: 06/10/12
05:02 AM

Ok new fuel pump helped but I got another problem I have a 750 demon double pumper and I have a lot of vapor coming out of front vent tube and it spits balls of gas out of it. If I put my finger over the vent tube my car dies instantly my impala(750 Holley) dads corvette(750 demon) buddy's mustang 750 Holley none of them have vapor coming out and I can plug the vent tube with my finger none of there cars die. When I drive just like normal driving my car slightly cuts out every few minutes and after a while car loads up and I can barely keep it running. I've checked fuel lines pressure reg three different carbs new distributer any ideas I have checked for intake leaks my intake is edelbrock performer
Thanks  

gallegos2005 gallegos2005
I love my Chevy Chevette! | Posts: 12 | Joined: 09/11
Posted: 06/10/12
05:06 AM

I have also lowered my float level and pulled my gas cap off  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 06/10/12
05:48 AM

a few things...

you could have clogged air bleeds ... there are 4 of them for the primaries.. and 4 for the secondaries..

you don't have to take them out to clean them.. just take a look... i normally use some carb spray through them...

i have also.. revved the engine.. and put my hand over the primary so i created massive amounts of fuel being pulled upwards through all the opening..   warning.. you can foul your spark plugs doing this.. i normally bring the RPMs up and let the spark plugs clear ..i don't stall the motor completely doing this..

this is where i would start...

if you have a friend with a wire feed welder.. i have found that the 0.023" welding wire.. i have some in stainless.. is just perfect for doing all kind of cleaning jobs on the tiny passages..


when the engine is operating.. vacuum is created as the air is flowing through the narrowing of the venturi..  this reduced pressure pulls fuel up in the main wells... where it comes up and over from the booster venturis..  to finely calibrate the system.. air bleeds allow fine tuning so you don't get a solid flow of fuel... you get a speed proportional discharge of fuel..

the air is being pulled into the air bleeds.. any debris or dirt.. can clog them..  

gallegos2005 gallegos2005
I love my Chevy Chevette! | Posts: 12 | Joined: 09/11
Posted: 06/12/12
05:49 AM

I have soaked the demon in gallon of carb cleaner and have also tryed other carbs including a Holley all have same result. I also put the 750 demon on my dads corvette and no vapor comes out and doesn't die when I put my fingure over vent tube. Do u think my cam is going bad?  

SDRods SDRods
I love my Chevy Chevette! | Posts: 1 | Joined: 07/12
Posted: 07/14/12
07:22 PM

You mentioned vapor from the demon. What fuel pump are you running, and how much pressure. Keep in mind in most stock applications, or aftermarket the needles and seats can't handle more than 6lbs fuel pressure. Just a thought that it may be the reason why its loading up, but ultimately you may larger issues. Also did you do a full rebuild of the carb? Never heard of this vapor issue before and I have ran and built alot of Holley's.  

gallegos2005 gallegos2005
I love my Chevy Chevette! | Posts: 12 | Joined: 09/11
Posted: 11/06/12
09:34 AM

This is for anybody with the same problem searching the Internet has found any  Answers it turned out to be a hole in my fuel line acting like the gas is boiling and brand new fuel pump was bad not producing enough fuel pressure.  

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